Adaptive threshold adjusting method for non-contact intelligent card demodulation system

A technology of self-adaptive threshold and demodulation system, which is applied in the direction of recording carriers, instruments, computer parts, etc. used by machines

Active Publication Date: 2014-02-26
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This technology allows automatic selection of specific thresholds on different types of signals used by wireless communication devices such as radios or microwave receivers at 1 mW levels (the minimum power level required). By doing this it ensures accurate demodulation results with no interruptions during peak periods when there are many other users transmitting their messages simultaneously without affecting each others' reception quality.

Problems solved by technology

This patented describes how electronic devices like credit or debit cards use their memory chip instead of magnetic stripes to store important personal details about them. However, it has been found through experiments involving various fields and environments where these memories change frequently over time. These variations make accurate analysis difficult without error correction techniques.

Method used

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  • Adaptive threshold adjusting method for non-contact intelligent card demodulation system
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  • Adaptive threshold adjusting method for non-contact intelligent card demodulation system

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Embodiment Construction

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] The structural block diagram of the non-contact smart card demodulation system of the present invention is as follows Figure 6 As shown, the flow chart of the adaptive threshold adjustment method involved in the present invention is as follows Figure 8 shown. Threshold automatic adjustment includes the following steps:

[0039] Step 1, the analog front end obtains the DC voltage and clock required for the contactless smart card from the RF carrier signal received by the antenna through the rectification and stabilization circuit and the clock recovery circuit;

[0040] Step 2: The smart card enters the site for power-on initialization configuration: set the upper limit of judgment counting times CNT_TIMES to 100, and the upper limit of the number of allowed zeros NUM0 to 3. The highest threshold Vmax=550mV for threshold adjustment, the lowest thr

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Abstract

The invention discloses an adaptive threshold adjusting method for a non-contact intelligent card demodulation system. An additionally-arranged adaptive threshold adjusting circuit in a non-contact IC card is utilized for accomplishment. The adaptive threshold adjusting circuit determines whether a threshold is appropriate according to the number of zeros in a zero number counter. After stabilization of a power-on simulation front end circuit, adjustment is carried out from a greatest threshold downwards, the great number of the zeros means that the threshold is too great, burr generation occurs, a fixed threshold step length is subtracted from a present threshold, after accomplishment of threshold switching of the simulation circuit, next determination is carried out continuously, till the number of the zeros reaches a prescribed range, the threshold reaches an optimum one, or demodulation for a smallest threshold is carried out. According to the adaptive threshold adjusting method, in a field intensity range of 1.5A/m-7.5A/m, for multiple antenna waveforms prescribed in an ISO/IEC14443TypeA protocol, a comparator threshold can be automatically selected, and demodulation data with pause width close to 3mus is outputted.

Description

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Claims

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Application Information

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Owner BEIJING UNIV OF TECH
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